Declaring a runway 'wet'
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From: Hogwarts
Declaring a runway 'wet'
I wonder if you GRND and TWR guys could help with this one:-
By definition in EU-ops:
A runway is considered 'wet' when the runway surface is covered with water or equivalent, less than 3mm or when there is sufficient moisture on the runway surface to cause it to appear reflective, but without significant areas of standing water. (Paraphrased)
&:
A runway is considered 'damp' when the surface is not dry but when the moisture on it does not give it a shiny appearance.
If the runway is grooved like for example LCY, even moderate rain (tell me if I'm wrong here) is not normally be enough to cause it to appear reflective. In this case can you declare the RW damp instead of wet??
Quite a few operators will not be able to operate in and out on LCY, or Oxford, Dundee etc. in 'wet' conditions. I have landed at LCY with the RW declared 'wet', but it was not shiny so according to the criteria above it should have been declared 'damp'.
There is a new Fodcom 03/2009 which states the UK AOC holders now have to use 'wet' performance even for grooved runways which are declared 'wet'.
If the runway is not declared 'wet', but 'damp' as it is non-reflective, then this will allow dry landing performace to be used. If not, then LCY for example will probably become a very quiet airport every time it rains!
By definition in EU-ops:
A runway is considered 'wet' when the runway surface is covered with water or equivalent, less than 3mm or when there is sufficient moisture on the runway surface to cause it to appear reflective, but without significant areas of standing water. (Paraphrased)
&:
A runway is considered 'damp' when the surface is not dry but when the moisture on it does not give it a shiny appearance.
If the runway is grooved like for example LCY, even moderate rain (tell me if I'm wrong here) is not normally be enough to cause it to appear reflective. In this case can you declare the RW damp instead of wet??
Quite a few operators will not be able to operate in and out on LCY, or Oxford, Dundee etc. in 'wet' conditions. I have landed at LCY with the RW declared 'wet', but it was not shiny so according to the criteria above it should have been declared 'damp'.
There is a new Fodcom 03/2009 which states the UK AOC holders now have to use 'wet' performance even for grooved runways which are declared 'wet'.
If the runway is not declared 'wet', but 'damp' as it is non-reflective, then this will allow dry landing performace to be used. If not, then LCY for example will probably become a very quiet airport every time it rains!
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From: Europe
Yep, you're right - for example at my airport we have 2 runways, 1 being grooved, and quite often we have 1 damp, 1 wet. But what you have to bear in mind is it's duty officer's job to check and declare runway condition, not ATC's.
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From: Tracey Island
There is a fine line between Wet and Damp. On some occasions it is a difficult call and the person inspecting will err on the side of caution and call it wet.
The other thing to remember is that quite often there is a lag between the Rwy drying out and an inspection, especially on a windy day or indeed vice versa when rain appears suddenly.
The best definition I've seen of damp is 'If you can sit on it without soaking your pants then it's damp'. Never tried it as a test but I'm assured it's accurate.
I've spoken to pilots who say that when a Rwy is called damp they treat it as a wet call. Sometimes we just can't win.
Remember if you want it checking again you are perfectly entitled to ask before your take off. If you can take the wait at the hold.....
The other thing to remember is that quite often there is a lag between the Rwy drying out and an inspection, especially on a windy day or indeed vice versa when rain appears suddenly.
The best definition I've seen of damp is 'If you can sit on it without soaking your pants then it's damp'. Never tried it as a test but I'm assured it's accurate.
I've spoken to pilots who say that when a Rwy is called damp they treat it as a wet call. Sometimes we just can't win.
Remember if you want it checking again you are perfectly entitled to ask before your take off. If you can take the wait at the hold.....
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Here is what the UK instructions to controllers says:
I though the same information was in the AIP but I couldn't find it when I had a quick look just now.
I think these rules came in when JAR-OPS was introduced and pilots started asking whether the runway was contaminated or not. This caused some confusion - from what I recall, JAR-OPS considered a runway contaminated (and thus needed the use of particular sets of performance data) when it was wet or worse whereas airports and ATC generally thought of contaminated as covered in de-icer or similar.
From where I sat in the day job at the time it looked like JAA had developed a fine set of rules for aircraft operation for assessing runway state.......but didn't look at what ICAO said would actually be reported by airports and ATC!
1 Introduction
1.1 It is recognised that a need exists to warn pilots of the presence of water on a runway. The Aerodrome Authority is responsible for assessing runway surface conditions.
1.2 When the presence of water on a runway is brought to the attention of the controller, the information shall be passed to aircraft.
2 Reporting Wet Runways
2.1 The presence or otherwise of surface water on a runway is to be reported on the RTF and ATIS, in plain language, using the following descriptions:
Reporting Term Surface conditions
DRY The surface is not affected by water, slush, snow, or ice.
NOTE: Reports that the runway is dry are not normally to be passed to pilots. If no runway surface report is passed, pilots will assume the surface to be dry.
DAMP The surface shows a change of colour due to moisture.
NOTE: If there is sufficient moisture to produce a surface film or the surface appears reflective, the runway will be reported as WET.
WET The surface is soaked but no significant patches of standing water
are visible.
NOTE: Standing water is considered to exist when water on the runway surface is deeper than 3mm. Patches of standing water covering more than 25% of the assessed area will be reported as WATER PATCHES.
WATER PATCHES Significant patches of standing water are visible.
NOTE: Water patches will be reported when more than 25% of the assessed area is covered by water more than 3mm deep.
FLOODED Extensive patches of standing water are visible.
NOTE: Flooded will be reported when more than 50% of the assessed area is covered by water more than 3mm deep.
2.2 When reported, the presence or otherwise of surface water on a runway will be assessed over the most significant portion of the runway, i.e. the area most likely to be used by aircraft taking-off and landing. This area may differ slightly from one runway to another but will approximate to the central two-thirds of the width of the runway extending longitudinally from a point 100 m before the aiming point to 100 m beyond the aiming point for the reciprocal runway. The assessed area may be different on runways with a displaced threshold or other unusual configuration, e.g. starter extension. The Aerodrome Authority is responsible for determining the exact dimensions and location of the area that is assessed.
2.3 Reports of the runway to be used include, sequentially, the conditions in each third of the assessed area. For example, “Runway surface is wet, water patches, wet” or “Runway surface is wet, wet, wet”.
2.4 A brief description of any water patches greater than 9mm in depth, which may affect engine performance, will be appended to a runway surface condition report. In such conditions, further information on the location, extent and depth of the water patches will be available from the Aerodrome Authority.
2.5 A brief description of any notable quantity of water outside the assessed area, e.g. water collected at the runway edge, will be appended to a runway surface condition report.
1.1 It is recognised that a need exists to warn pilots of the presence of water on a runway. The Aerodrome Authority is responsible for assessing runway surface conditions.
1.2 When the presence of water on a runway is brought to the attention of the controller, the information shall be passed to aircraft.
2 Reporting Wet Runways
2.1 The presence or otherwise of surface water on a runway is to be reported on the RTF and ATIS, in plain language, using the following descriptions:
Reporting Term Surface conditions
DRY The surface is not affected by water, slush, snow, or ice.
NOTE: Reports that the runway is dry are not normally to be passed to pilots. If no runway surface report is passed, pilots will assume the surface to be dry.
DAMP The surface shows a change of colour due to moisture.
NOTE: If there is sufficient moisture to produce a surface film or the surface appears reflective, the runway will be reported as WET.
WET The surface is soaked but no significant patches of standing water
are visible.
NOTE: Standing water is considered to exist when water on the runway surface is deeper than 3mm. Patches of standing water covering more than 25% of the assessed area will be reported as WATER PATCHES.
WATER PATCHES Significant patches of standing water are visible.
NOTE: Water patches will be reported when more than 25% of the assessed area is covered by water more than 3mm deep.
FLOODED Extensive patches of standing water are visible.
NOTE: Flooded will be reported when more than 50% of the assessed area is covered by water more than 3mm deep.
2.2 When reported, the presence or otherwise of surface water on a runway will be assessed over the most significant portion of the runway, i.e. the area most likely to be used by aircraft taking-off and landing. This area may differ slightly from one runway to another but will approximate to the central two-thirds of the width of the runway extending longitudinally from a point 100 m before the aiming point to 100 m beyond the aiming point for the reciprocal runway. The assessed area may be different on runways with a displaced threshold or other unusual configuration, e.g. starter extension. The Aerodrome Authority is responsible for determining the exact dimensions and location of the area that is assessed.
2.3 Reports of the runway to be used include, sequentially, the conditions in each third of the assessed area. For example, “Runway surface is wet, water patches, wet” or “Runway surface is wet, wet, wet”.
2.4 A brief description of any water patches greater than 9mm in depth, which may affect engine performance, will be appended to a runway surface condition report. In such conditions, further information on the location, extent and depth of the water patches will be available from the Aerodrome Authority.
2.5 A brief description of any notable quantity of water outside the assessed area, e.g. water collected at the runway edge, will be appended to a runway surface condition report.
I think these rules came in when JAR-OPS was introduced and pilots started asking whether the runway was contaminated or not. This caused some confusion - from what I recall, JAR-OPS considered a runway contaminated (and thus needed the use of particular sets of performance data) when it was wet or worse whereas airports and ATC generally thought of contaminated as covered in de-icer or similar.
From where I sat in the day job at the time it looked like JAA had developed a fine set of rules for aircraft operation for assessing runway state.......but didn't look at what ICAO said would actually be reported by airports and ATC!
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From: Madrid FIR
A couple of years ago I remember passing our runway state as 'damp' to a landing aircraft. The pilot wouldn't accept this, and insisted I pass either 'dry' or 'wet'. Something to do with autobrake settings I think. Any comments from aircrew about how your aircraft operating manual treats calls of 'damp' runways?
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From: Hogwarts
Thanks for all the great answers.
Call 100: I've never tried the wet trouser test yet!
It seems that the ICAO 'Water patches' is equivalent to 'contaminated' in Jar-ops and presumably under EU -Ops also, which is >3mm water over 25% of RW (or by slush or looses snow equivalent to >3mm, or compacted snow or wet ice) (Paraphrased)
'Wet' could mean up to 3mm of water, which would cause quite a big risk of aquaplaning. This is probably why we need an extra 15% of LDA.
Under EU-Ops, the LDR may not be more than 60% of the LDA for a dry RW. If you turn this around. The LDA need to be at least 1.66 of LDR. But for 'wet' it is 1.92. This extra factor for 'wet' means that a fair number of a/c will not be able to land (or t/o) in 'wet' conditions at say LCY.
For EU-Ops, 'damp' performance figures are the same as 'dry'. Which is why we all love grooved runways which can be declared no worse than damp in all but heavy rain. (as long as the RW 'does not appear reflective'!)
Practically speaking, the stopping distance on a runway with up to 3mm of water compared with that on a grooved runway which is draining effectively is bound to be much greater. (with anti-skid in both cases).This is could be the difference between 'wet' and 'damp'.
With FOCOM 3/2009 operators are no longer allowed to assume a grooved RW to be 'damp' (and use 'dry' performance) if it has been declared 'wet'.
To conclude, it will help us all out (Operaters, ATC, & airport authorities) if runways are declared no worse than 'damp' unless they, as they say in the good book, 'appear reflective', otherwise declare them 'damp'.
Call 100: I've never tried the wet trouser test yet!
It seems that the ICAO 'Water patches' is equivalent to 'contaminated' in Jar-ops and presumably under EU -Ops also, which is >3mm water over 25% of RW (or by slush or looses snow equivalent to >3mm, or compacted snow or wet ice) (Paraphrased)
'Wet' could mean up to 3mm of water, which would cause quite a big risk of aquaplaning. This is probably why we need an extra 15% of LDA.
Under EU-Ops, the LDR may not be more than 60% of the LDA for a dry RW. If you turn this around. The LDA need to be at least 1.66 of LDR. But for 'wet' it is 1.92. This extra factor for 'wet' means that a fair number of a/c will not be able to land (or t/o) in 'wet' conditions at say LCY.
For EU-Ops, 'damp' performance figures are the same as 'dry'. Which is why we all love grooved runways which can be declared no worse than damp in all but heavy rain. (as long as the RW 'does not appear reflective'!)
Practically speaking, the stopping distance on a runway with up to 3mm of water compared with that on a grooved runway which is draining effectively is bound to be much greater. (with anti-skid in both cases).This is could be the difference between 'wet' and 'damp'.
With FOCOM 3/2009 operators are no longer allowed to assume a grooved RW to be 'damp' (and use 'dry' performance) if it has been declared 'wet'.
To conclude, it will help us all out (Operaters, ATC, & airport authorities) if runways are declared no worse than 'damp' unless they, as they say in the good book, 'appear reflective', otherwise declare them 'damp'.
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It seems that the ICAO 'Water patches' is equivalent to 'contaminated' in Jar-ops and presumably under EU -Ops also, which is >3mm water over 25% of RW (or by slush or looses snow equivalent to >3mm, or compacted snow or wet ice) (Paraphrased)
2.9.4 Recommendation.— Whenever water is present on a runway, a description of the runway surface conditions on the centre half of the width of the runway, including the possible assessment of water depth, where applicable, should be made available using the following terms:
DAMP — the surface shows a change of colour due to moisture.
WET — the surface is soaked but there is no standing water.
WATER PATCHES — significant patches of standing water are visible.
FLOODED — extensive standing water is visible.
And note that this is only a recommended practice. Maybe there is more written in other docs but I'm not aware of it.
BTW, I found the UK AIP entry that I was looking for - its para 15 in AIP link. It's more specific about the implications for performance calculations and accords with your comments on EU-Ops.
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From: Hogwarts
Thanks Spitoon for correcting me.
As you say it comes from the AIP. But the 'note' attached to the DAMP description is very important. This is in agreement with EU-Ops.
'DAMP — the surface shows a change of colour due to moisture.
Note: If there is sufficient moisture to produce a surface film or the surface appears reflective the runway will be reported WET.'
All we need is to somehow ensure that on wet days, the runway is correctly reported as 'DAMP' unless unless 'the surface appears reflective' as above.
Then we can legally operate in and out of LCY in all but heavy rain.
See: FODCOM 3/2009
As you say it comes from the AIP. But the 'note' attached to the DAMP description is very important. This is in agreement with EU-Ops.
'DAMP — the surface shows a change of colour due to moisture.
Note: If there is sufficient moisture to produce a surface film or the surface appears reflective the runway will be reported WET.'
All we need is to somehow ensure that on wet days, the runway is correctly reported as 'DAMP' unless unless 'the surface appears reflective' as above.
Then we can legally operate in and out of LCY in all but heavy rain.
See: FODCOM 3/2009
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Not meant as a correction........just an extra bit of info that I should of thought of when I posted earlier.
I think the UK went further than ICAO because some pilots queried the basic reports. What puzzled me was that so few pilots (that presumably were operating to JAR-OPS) wanted any more information.
I think the UK went further than ICAO because some pilots queried the basic reports. What puzzled me was that so few pilots (that presumably were operating to JAR-OPS) wanted any more information.
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From: Hogwarts
Thenks very much for all the info, Spitoon.
I just wanted to highlight the implications for us operators with regard to 'wet' vs 'damp' reports on runway state, especially after FODCOM 3/09. and I think we could have a way living with it.
D
I just wanted to highlight the implications for us operators with regard to 'wet' vs 'damp' reports on runway state, especially after FODCOM 3/09.
and I think we could have a way living with it.D
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From: Scotland
FODCOM 03/2009 is kind of interesting in that UK AOC Operators may not treat a Wet grooved runway as Dry, but the rest of Europe does - are we now into the scenario where UK AOC Operators can't land but other European AOC Operators can?
"I no longer fly with ze crazy British Airline, when it rains we cannot land"
So much for the level playing field in Europe brought about by EU-OPS.
It is interesting to note that in 2003 JAR-25.109(d) (Now CS-25) (well after JAR-OPS) was amended to include "Wet Grooved performance", which can be calculated on the basis that braking action on Wet grooved runway is seven times better than wet braking action on a smooth wet runway (Dry braking action is ten times better than that on a smooth wet runway). From the wording in JAR-25 and CS-25 wet grooved performance can be calculated, rather than flight testing required. Ideally manufacturers should retrospectively amend aircraft flight manuals to reflect this.
"I no longer fly with ze crazy British Airline, when it rains we cannot land"
So much for the level playing field in Europe brought about by EU-OPS.
It is interesting to note that in 2003 JAR-25.109(d) (Now CS-25) (well after JAR-OPS) was amended to include "Wet Grooved performance", which can be calculated on the basis that braking action on Wet grooved runway is seven times better than wet braking action on a smooth wet runway (Dry braking action is ten times better than that on a smooth wet runway). From the wording in JAR-25 and CS-25 wet grooved performance can be calculated, rather than flight testing required. Ideally manufacturers should retrospectively amend aircraft flight manuals to reflect this.
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From: Hogwarts
'It is interesting to note that in 2003 JAR-25.109(d) (Now CS-25) (well after JAR-OPS) was amended to include "Wet Grooved performance", which can be calculated on the basis that braking action on Wet grooved runway is seven times better than wet braking action on a smooth wet runway (Dry braking action is ten times better than that on a smooth wet runway).'
Oldflyer,
That's excellent stuff. I wonder if EU-Ops has left that bit unchanged? This reinforces my point that there is practically a big difference in braking action between stopping distance on a wet (i.e. covered in up to 3mm water) runway and on a well drained 'so called wet' grooved runway.
A duty officer, who checks a grooved runway can be reassured of this fact when he/she declares the runway technically 'damp', instead of erring on the side of caution and declaring it 'wet'.
I haven't noticed that I use any more RW at LCY on wet days compared with dry.
FODCOM 3/09 has given UK Operators just another deviation from EU-OPS to contend with.
Oldflyer,
That's excellent stuff. I wonder if EU-Ops has left that bit unchanged? This reinforces my point that there is practically a big difference in braking action between stopping distance on a wet (i.e. covered in up to 3mm water) runway and on a well drained 'so called wet' grooved runway.
A duty officer, who checks a grooved runway can be reassured of this fact when he/she declares the runway technically 'damp', instead of erring on the side of caution and declaring it 'wet'.
I haven't noticed that I use any more RW at LCY on wet days compared with dry.
FODCOM 3/09 has given UK Operators just another deviation from EU-OPS to contend with.
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From: Hogwarts
PS I found the reference you mentioned in EU-ops CS-25.109(d). It allows operators more leeway with 'wet' grooved runways.
Unfortunately, as you know, us poor UK operators have the UK AIP to contend with when using a grooved runway declared 'wet'.
Unfortunately, as you know, us poor UK operators have the UK AIP to contend with when using a grooved runway declared 'wet'.
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From: UK
Might I just add some info .... declaring a runway wet or dry can be done from a visual inspection without physically touching the runway surface.... i.e from an adjacent taxiway.
The most common use of this is when changing from dry to wet. When a rain shower/squall has just gone through and it's clearly wet but traffic may be busy and it's blindingly obvious (i.e. the spray thrown up by the last landing a/c
) ...... the transition to dry tends to be slower and more likely to be done through close physical inspection ...
To declare the surface "damp" requires a physical inspection of the surface.
I too have been told the "sit on it" method but the more common usage is to place a hand on the grooved surface and check for cold/clammy/moisture feelings!!
The most common use of this is when changing from dry to wet. When a rain shower/squall has just gone through and it's clearly wet but traffic may be busy and it's blindingly obvious (i.e. the spray thrown up by the last landing a/c
) ...... the transition to dry tends to be slower and more likely to be done through close physical inspection ... To declare the surface "damp" requires a physical inspection of the surface.
I too have been told the "sit on it" method but the more common usage is to place a hand on the grooved surface and check for cold/clammy/moisture feelings!!
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From: Hogwarts
'To declare the surface "damp" requires a physical inspection of the surface'
That's worth knowing. There could be a difference between the ATC and duty officer's version of 'damp' and that of the operators.
From the AIP:
'DAMP — the surface shows a change of colour due to moisture.
Note: If there is sufficient moisture to produce a surface film or the surface appears reflective the runway will be reported WET.'
If I see that a so-called 'wet' runway is not shiny at all, I would call that 'damp' and therefore I would land using 'dry' performance. On short final, the pilots will sometimes have a better view of the runway than anyone, depending on the lighting etc. The trouble is, I'm not sure how legal that is. Most pilots will probably just divert from say LCY if it is declared 'wet' and if they can't land in 'wet' conditions since FODCOM 3/09.
Also I wonder how an A318 will do in 'wet' conditions at LCY?
That's worth knowing. There could be a difference between the ATC and duty officer's version of 'damp' and that of the operators.
From the AIP:
'DAMP — the surface shows a change of colour due to moisture.
Note: If there is sufficient moisture to produce a surface film or the surface appears reflective the runway will be reported WET.'
If I see that a so-called 'wet' runway is not shiny at all, I would call that 'damp' and therefore I would land using 'dry' performance. On short final, the pilots will sometimes have a better view of the runway than anyone, depending on the lighting etc. The trouble is, I'm not sure how legal that is. Most pilots will probably just divert from say LCY if it is declared 'wet' and if they can't land in 'wet' conditions since FODCOM 3/09.
Also I wonder how an A318 will do in 'wet' conditions at LCY?
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From: Tracey Island
Of course you are assuming that the wet or dry call is water. Today we had a damp runway, damp with the remains of de-icing fluid. With the bright sunshine we had, the surface gained a sheen but was not wet....
Sorry to add to the confusion.
Quite often the runway will dry out before it is inspected so there is a lag there. I've seen runways with all three sectors having a different call Dry, Damp, Wet.
Damp, Dry, Damp.
Dry, Wet, Dry etc. etc.
Some days are just a nightmare dependent on the weather conditions for the day.
At the end of the day we call it for the Pilot. So, if he wants it rechecking that's what he gets.
Sorry to add to the confusion.
Quite often the runway will dry out before it is inspected so there is a lag there. I've seen runways with all three sectors having a different call Dry, Damp, Wet.
Damp, Dry, Damp.
Dry, Wet, Dry etc. etc.
Some days are just a nightmare dependent on the weather conditions for the day.
At the end of the day we call it for the Pilot. So, if he wants it rechecking that's what he gets.
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From: UK
Dumbledor
I think you are slightly miss-understanding what is being said in regards to a damp and wet runway.
The runway can still be wet providing it is 'soaked', and there is no need for there to be surface film or reflective.
However, it cannot be reported as damp if either of these exist.
It seems quite clear that so long as the surface is 'soaked' then it should be reported as wet regardless of reflective or not.
DAMP The surface shows a change of colour due to moisture.
NOTE: If there is sufficient moisture to produce a surface film or the surface appears reflective, the runway will be reported as WET.
WET The surface is soaked but no significant patches of standing water are visible.
NOTE: Standing water is considered to exist when water on the runway surface is deeper than 3mm. Patches of standing water covering more than 25% of the assessed area will be reported as WATER PATCHES.
NOTE: If there is sufficient moisture to produce a surface film or the surface appears reflective, the runway will be reported as WET.
WET The surface is soaked but no significant patches of standing water are visible.
NOTE: Standing water is considered to exist when water on the runway surface is deeper than 3mm. Patches of standing water covering more than 25% of the assessed area will be reported as WATER PATCHES.
However, it cannot be reported as damp if either of these exist.
It seems quite clear that so long as the surface is 'soaked' then it should be reported as wet regardless of reflective or not.
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From: Hogwarts
Thanks for the replies. I suppose I left out the 'soaked' bit as I assumed that to be more towards the wetter end of the 'wet' spectrum (if that makes sense) and in no way close to the 'damp' definition. I can't imagine why a soaked runway would not appear shiny or reflective, but moving on swiftly...
Thanks for the deicing fluid point. We don't have performance data for when the RW is wet with this. That would be an airmanship issue. It is worth bearing in mind that 'wet' can mean up to 3mm water, which is the worst case scenario which is what are performance charts should be calculated for (how the 3mm is measured is another story ...?) and hence the extra 15% LDR etc.
Criss wrote: 'at my airport we have 2 runways, 1 being grooved, and quite often we have 1 damp, 1 wet.'
It is probable at other airports (worldwide) that the grooved runway (if they owned it!) in this example would be declared 'wet' incorrectly. This would halt movemets for some operators under the latest CAA ruling. (FODCOM 3/09)
That is my main point/concern.
Thanks for the deicing fluid point. We don't have performance data for when the RW is wet with this. That would be an airmanship issue. It is worth bearing in mind that 'wet' can mean up to 3mm water, which is the worst case scenario which is what are performance charts should be calculated for (how the 3mm is measured is another story ...?) and hence the extra 15% LDR etc.
Criss wrote: 'at my airport we have 2 runways, 1 being grooved, and quite often we have 1 damp, 1 wet.'
It is probable at other airports (worldwide) that the grooved runway (if they owned it!) in this example would be declared 'wet' incorrectly. This would halt movemets for some operators under the latest CAA ruling. (FODCOM 3/09)
That is my main point/concern.
